Electronic apparatus

ABSTRACT

An electronic apparatus includes: a circuit board that is mounted with a first heat generating component and a second heat generating component that generate heat; and a circulation-type heat pipe that circulates a coolant, the heat pipe including: a first heat reception part that receives heat from the first heat generating component, the first heat reception part being provided with a wick for evaporating the coolant to serve as an evaporation part; a second heat reception part that receives heat from the second heat generating component and circulates the coolant to the first heat reception part; and a condensation part that condenses the coolant circulated from the first heat reception part, the condensation part being provided between the first heat reception part and the second heat reception part.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2007-224392, filed on Aug. 30, 2007, the entire content of which are incorporated herein by reference.

BACKGROUND

1. Field

One embodiment of the invention relates to an electronic apparatus having a heat pipe for cooling a plurality of heat generating components mounted on a circuit board.

2. Description of the Related Art

An example of a circulation-type heat pipe is disclosed in JP-A-2006-125783. In the circulation-type heat pipe according to the related art, an evaporation part heated from outside and a condensation part for diffusing heat are made to communicate with each other so as to form a circulating flow path by a steam pipe and a liquid pipe, and a working fluid evaporated upon heating and condensed upon diffusion is sealed into the circulating flow path. A wick structure for causing a capillary pressure to occur is provided in the liquid pipe and the capillary pressure produced by the wick structure causes the working fluid to circulate through the circulating flow path.

In an electronic apparatus, if a plurality of heat generating components (for example, integrated circuits such as a CPU and a north bridge) are mounted on a board, a cooling unit needs to be provided for cooling the heat generating components. It is desirable that the heat generating components should be efficiently cooled using a circulation-type heat pipe.

SUMMARY

According to a first aspect of the present invention, there is provided an electronic apparatus including: a circuit board that is mounted with a first heat generating component and a second heat generating component that generate heat; and a circulation-type heat pipe that circulates a coolant, the heat pipe including: a first heat reception part that receives heat from the first heat generating component, the first heat reception part being provided with a wick for evaporating the coolant to serve as an evaporation part; a second heat reception part that receives heat from the second heat generating component and circulates the coolant to the first heat reception part; and a condensation part that condenses the coolant circulated from the first heat reception part, the condensation part being provided between the first heat reception part and the second heat reception part.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

A general configuration that implements the various feature of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention.

FIG. 1 is a perspective view to show a notebook personal computer.

FIG. 2 is a drawing to show a cooling unit according to a first embodiment of the present invention.

FIG. 3 is a sectional view of a part of a heat pipe.

FIG. 4 is a drawing to show a cooling unit according to a second embodiment of the present invention.

FIG. 5 is a drawing to show a cooling unit according to a third embodiment of the present invention.

FIG. 6 is a drawing to show a cooling unit according to a fourth embodiment of the present invention.

FIG. 7 is a drawing to show a cooling unit according to a fifth embodiment of the present invention.

DETAILED DESCRIPTION

Referring now to the accompanying drawings, there are shown preferred embodiments of the present invention. In the following description, identical components or components having identical functions are denoted by the same reference numerals to omit redundant description therefor.

First Embodiment

FIG. 1 is a perspective view to show the appearance of a notebook personal computer 10, which is shown as an exemplary electronic apparatus according to the present invention. The notebook personal computer 10 includes: a main unit 11 having operation devices, such as a keyboard 13 and a touch pad 16, provided on the top face; and a display unit 12 having a liquid crystal display panel 17 provided at the front. A hinge is provided in the left and right corners at the back of the main unit 11, and the display unit 12 is attached to be pivot between an open position and a closed position relative to the main unit 11. The main unit 11 has a thin box-shaped casing 18 on which the keyboard 13, a power button 14 for turning on/off power of the computer 10, an input operation panel 15, the touch pad 16, and the like are placed.

FIG. 2 is a plan view of the inside of a back left area R of the computer 10 from above. As shown in FIG. 2, a printed circuit board 20 is accommodated in the casing 18. A first circuit component 21, a second circuit component 22, and a third circuit component 23, which serve as heat generating components, are mounted on the printed circuit board 20. The first circuit component 21 is a CPU (Central Processing Unit) and is a circuit component involving the maximum calorific value among the circuit components mounted on the printed circuit board 20. The second circuit component 22 and the third circuit component 23 are semiconductor integrated circuits (LSI: Large-Scale Integration), such as one of a VGA (Video Graphics Array), a north bridge, or a south bridge. The circuit components 21, 22, and 23 have each a large calorific value during the operation and require cooling to maintain stable operation. Then, to cool the circuit components 21, 22, and 23, a cooling unit 30 is accommodated in the casing 18.

The cooling unit 30 according to a first embodiment includes circulation-type heat pipe parts 31 to 36, a fin assembly 37 of a heat sink, and an electric fan unit 38. The members configuring the cooling unit 30 are disposed in the vicinity of exhaust ports 19 made in a side wall of the casing 18 of the main unit 11.

The circulation-type heat pipe parts 31 to 36 cool the circuit components 21, 22, and 23 by internally circulating a coolant. The heat pipe parts 31 to 36 are formed by overlapping and joining two thin plate members and are members formed like a thin plate as a whole. The heat pipe parts 31 to 36 are formed inside with coolant flow paths 39 for circulating a coolant. For example, the heat pipe part 34 is formed by piling up and joining an upper thin plate member 34 a and a lower thin plate member 34 b as shown in FIG. 3 (cross section taken on line III-III in FIG. 2). The lower thin plate member 34 b is formed on a joint face with a plurality of (in the embodiment, three) grooves, which form the coolant flow paths 39. Although water is used as the coolant in the embodiment, other liquid may be used.

A first heat reception part 31, a second heat reception part 35, and a third heat reception part 36 are formed at midpoints in the heat pipe parts 31 to 36. The first heat reception part 31 is a part abutting the first circuit component 21 of the heat pipe and receives heat from the first circuit component 21. The second heat reception part 35 is a part abutting the second circuit component 22 of the heat pipe and receives heat from the second circuit component 22. The third heat reception part 36 is a part abutting the third circuit component 23 of the heat pipe and receives heat from the third circuit component 23.

An evaporation part 31, a steam pipe 32, a condensation part 33, and a liquid pipe 34 are formed at midpoints in the coolant flow paths 39 of the heat pipe parts 31 to 36. The evaporation part 31 is a part at the same position as the first heat reception part 31 in the heat pipe. The condensation part 33 is a part at an intermediate position between the first heat reception part 31 and the second heat reception part 35 in the heat pipe.

The evaporation part 31 is a heat exchanger for evaporating a coolant flowing from the liquid pipe 34 and cooling the first circuit component 21. The evaporation part 31 is provided at a position corresponding to the first circuit component 21; specifically it is provided above the first circuit component 21. The evaporation part 31 is in intimate contact with the first circuit component 21 with a heat conduction member of grease, etc., between, and is thermally connected to the first circuit component 21 through the heat conduction member. In the embodiment, the coolant flow paths 39 meander in the evaporation part 31. Accordingly, the first circuit component 21 involving a comparatively large calorific value is cooled effectively by latent heat absorption when the coolant evaporates. To further effectively cool the first circuit component 21, the evaporation part 31 may be provided with a radiation fin of a heat sink.

The steam pipe 32 is provided to conduct coolant steam provided in the evaporation part 31 from the evaporation part 31 to the condensation part 33. The coolant steam moving in the steam pipe 32 is a gas and has a large volume and thus the flow path cross-sectional area of the steam pipe 32 is large as compared with that of the liquid pipe 34. That is, the groove formed in the lower thin plate member is comparatively deep in the steam pipe 32.

The condensation part 33 is a heat exchanger for cooling and condensing the coolant steam flowing from the steam pipe 32. It is disposed at a position inside the exhaust ports 19 of the casing. The fin assembly 37 having a large number of fins is joined to the top face of the condensation part 33. The fin assembly 37 is placed between a discharge port 38 b of the electric fan unit 38 and the exhaust ports 19 of the casing 18; air flow sent from the electric fan unit 38 is blown against the fin assembly 37. Heat of the coolant is transmitted from the condensation part 33 to the fin assembly 37 and further is discharged to the outside of the casing 18 through the exhaust ports 19 by air flow sent from the electric fan unit 38.

The liquid pipe 34 is provided to conduct the coolant condensed in the condensation part 33 via the second heat reception part 35 and the third heat reception part 36 to the evaporation part 31. The coolant flow paths 39 of the liquid pipe 34 are formed with a wick for conducting a coolant using a capillary force, and the coolant is conducted from the condensation part 33 to the evaporation part 31 by the wick. Since the heat pipe is thus configured so that the coolant circulates naturally, a pump, etc., to circulate the coolant is not required and the configuration of the cooling unit 30 is simplified. The coolant moving in the liquid pipe 34 is a liquid and has a small volume and thus the flow path cross-sectional area of the liquid pipe 34 is small as compared with that of the steam pipe 32. That is, the groove formed in the lower thin plate member is comparatively shallow in the liquid pipe 34. The coolant is warmed gradually by external heat while it passes through the liquid pipe 34. To suppress such a rise in temperature of the coolant, a heat sink (not shown) may be disposed in a state in which it is in intimate contact with the liquid pipe 34 for relieving the heat of the coolant passing through the liquid pipe 34 into the heat sink.

The second heat reception part 35 is a part of the liquid pipe 34 and is a heat exchanger for cooling the second circuit component 22. The second heat reception part 35 is provided at a position corresponding to the second circuit component 22; specifically it is provided above the second circuit component 22. The second heat reception part 35 is in intimate contact with the second circuit component 22 with a heat conduction member of grease, etc., between, and is thermally connected to the second circuit component 22 through the heat conduction member. In the second heat reception part 35, the coolant flow paths 39 travel in a straight line and thus the cooling amount of the second circuit component 22 by the coolant is comparatively small. The second circuit component 22 is cooled by sensible heat absorption when the temperature of the coolant rises. That is, in the second heat reception part 35, the coolant is warmed by heat of the second circuit component 22, but does not evaporate. Such cooling by sensible heat absorption is appropriate for cooling the third circuit component 23 involving a comparatively small calorific value.

The third heat reception part 36 is a part of the liquid pipe 34 and is a heat exchanger for cooling the third circuit component 23. The third heat reception part 36 is provided at a position corresponding to the third circuit component 23; specifically it is provided above the third circuit component 23. The third heat reception part 36 is in intimate contact with the third circuit component 23 with a heat conduction member of grease, etc., between, and is thermally connected to the third circuit component 23 through the heat conduction member. In the third heat reception part 36, the coolant flow paths 39 travel in a straight line and thus the cooling amount of the third circuit component 23 by the coolant is comparatively small. The third circuit component 23 is cooled by sensible heat absorption when the temperature of the coolant rises. That is, in the third heat reception part 36, the coolant is warmed by heat of the third circuit component 23, but does not evaporate. Such cooling by sensible heat absorption is appropriate for cooling the third circuit component 23 involving a comparatively small calorific value.

In the embodiment, the second heat reception part and the third heat reception part 36 are provided by bringing the linear portion of the liquid pipe 34 into intimate contact with the second circuit component 22 and the third circuit component 23, but the second heat reception part 35 and the third heat reception part 36 may be provided in another form. For example, the second heat reception part 35 may be provided by meandering the coolant flow paths 39 at the position corresponding to the second circuit component 22 like the evaporation part 31; further the second heat reception part 35 may be provided with a cooling fan to efficiently cool the second circuit component 22. Likewise, the third heat reception part 36 may be provided by meandering the coolant flow paths 39 at the position corresponding to the third circuit component 23; further the third heat reception part 36 may be provided with a cooling fan to efficiently cool the third circuit component 23. That is, the second heat reception part 35 and the third heat reception part 36 may be those for allowing the coolant to pass through the coolant flow paths with the liquid state maintained regardless of the shape.

The electric fan unit 38 contains an impeller driven by an electric motor. An admission port 38 a is provided in the center of the top of the electric fan unit 38, and the above-mentioned discharge port 38 b is provided on the exhaust ports 19 side of the electric fan unit 38. When the internal impeller rotates in the electric fan unit 38, air is sucked into the electric fan unit 38 through the admission port 38 a and is blown out from the inside of the electric fan unit 38 through the discharge port 38 b. The air blown out from the discharge port 38 b of the electric fan unit 38 cools the fin assembly 37 and is discharged to the outside of the casing 18 through the exhaust ports 19.

According to the cooling unit 30 of the embodiment, the first circuit component 21 can be cooled using the evaporation part 31 and the second circuit component 22 and the third circuit component 23 can also be cooled using the second heat reception part 35 and the third heat reception part 36. That is, the first circuit component 21 involving a comparatively large calorific value can be effectively cooled using latent heat absorption when the coolant evaporates. The second circuit component 22 and the third circuit component 23 involving a comparatively small calorific value can be appropriately cooled using sensible heat absorption when the temperature of the coolant rises. Therefore, a cooling method is selected in response to the calorific value of each of the first, second, and third circuit components 21, 22, and 23, whereby the optimum cooling unit for cooling the first, second, and third circuit components 21, 22, and 23 can be configured.

According to the cooling unit 30 of the embodiment, the heat pipe parts 31 to 36 are placed so as to pass through above the first, second, and third circuit components 21, 22, and 23, so that the circuit components 21, 22, and 23 can be cooled using one heat pipe made up of the heat pipe parts 31 to 36. If separate heat pipes are provided to each of the first, second, and third circuit components 21, 22, and 23, the space required for placing the heat pipes increases; however, to cool the circuit components 21, 22, and 23 using one heat pipe made up of the heat pipe parts 31 to 36 as in the embodiment, the space required for placing the heat pipe parts 31 to 36 can be lessened.

According to the cooling unit 30 of the embodiment, the liquid pipe 34 where a liquid coolant flows and the steam pipe 32 where coolant stream flows are independent pipe conduits, so that the coolant and the coolant steam do not become a counter current and the loss of the coolant flow is small. Consequently, the cooling efficiency for the cooling unit 30 to cool the first, second, and third circuit components 21, 22, and 23 can be enhanced.

Second Embodiment

Next, an electronic apparatus according to a second embodiment of the present invention will be discussed with reference to FIG. 4.

In a cooling unit 40 according to the second embodiment, a heat pipe is formed with a first evaporation part 41A that serves as a first heat reception part, a first steam pipe 42A, a first condensation part 43A, a first liquid pipe 44A, a second evaporation part 41B that serves as a second heat reception part, a second steam pipe 42B, a second condensation part 43B, a second liquid pipe 44B, and a third heat reception part 46. The first evaporation part 41A, the first steam pipe 42A, the first condensation part 43A, the first liquid pipe 44A, and the third heat reception part 46 are formed like the evaporation part 31, the steam pipe 32, the condensation part 33, the liquid pipe 34, and the heat reception part 36 of the first embodiment.

The second evaporation part 41B, the second steam pipe 42B, the second condensation part 43B, and the second liquid pipe 44B are additional components to the second embodiment. The second evaporation part 41B, the second steam pipe 42B, the second condensation part 43B, and the second liquid pipe 44B are the same components as the evaporation part 31, the steam pipe 32, the condensation part 33, the liquid pipe 34, and the heat reception part 36 of the first embodiment, but differ in placement positions in a casing 18 from the evaporation part 31, the steam pipe 32, the condensation part 33, the liquid pipe 34, and the heat reception part 36. A second electric fan unit 48B is additionally provided corresponding to the second condensation part 43B.

A coolant flowing into the first evaporation part 41A from the second liquid pipe 44B evaporates in the first evaporation part 41A and cools a first circuit component 21. In the first evaporation part 41A, coolant flow paths 49 meander and the first circuit component 21 involving a comparatively large calorific value is cooled effectively by latent heat absorption when the coolant evaporates. Then, when coolant steam provided in the first evaporation part 41A arrives at the first condensation part 43A through the first steam pipe 42A, it condenses in the first condensation part 43A. Heat of the coolant is transmitted from the first condensation part 43A to a fin assembly 47A and further is discharged to the outside of the casing 18 through exhaust ports 19 by air flow sent from a first electric fan unit 48A. Then, the coolant condensed in the first condensation part 43A flows out into the first liquid pipe 44A.

The coolant flowing into the second evaporation part 41B from the first liquid pipe 44A evaporates in the second evaporation part 41B and cools a second circuit component 22. In the second evaporation part 41B, the coolant flow paths 49 meander and the second circuit component 22 involving a comparatively large calorific value is cooled effectively by latent heat absorption when the coolant evaporates. Then, when coolant steam provided in the second evaporation part 41B arrives at the second condensation part 43B through the second steam pipe 42B, the coolant condenses in the second condensation part 43B. Heat of the coolant is transmitted from the second condensation part 43B to a fin assembly 47B and further is discharged to the outside of the casing 18 through exhaust ports 19B by air flow sent from a second electric fan unit 48B. Then, the coolant condensed in the second condensation part 43B flows out into the second liquid pipe 44B.

The coolant flowing through the second liquid pipe 44B passes through the third heat reception part 46 at a midpoint in the second liquid pipe 44B and cools a third circuit component 23. In the third heat reception part 46, the coolant flow paths 49 travel in a straight line and the third circuit component 23 involving a comparatively small calorific value is cooled appropriately by sensible heat absorption when the temperature of the coolant rises.

According to the cooling unit 40 of the embodiment, the first circuit component 21 and the second circuit component 22 can be cooled using the first evaporation part 41A and the second evaporation part 41B and the third circuit component 23 can also be cooled using the third heat reception part 46. That is, the first circuit component 21 and the second circuit component 22 involving a comparatively large calorific value can be effectively cooled using latent heat absorption when the coolant evaporates. The third circuit component 23 involving a comparatively small calorific value can be appropriately cooled using sensible heat absorption when the temperature of the coolant rises. Therefore, a cooling method is selected in response to the calorific value of each of the first, second, and third circuit components 21, 22, and 23, whereby the optimum cooling unit 40 for cooling the first, second, and third circuit components 21, 22, and 23 can be configured.

According to the cooling unit 40 of the embodiment, the heat pipe parts 41 to 46 are placed so as to pass through above the first, second, and third circuit components 21, 22, and 23, so that the circuit components 21, 22, and 23 can be cooled using one heat pipe made up of the heat pipe parts 41 to 46. If separate heat pipes are provided to each of the first, second, and third circuit components 21, 22, and 23, the space required for placing the heat pipes increases; however, to cool no the circuit components 21, 22, and 23 using one heat pipe made up of the heat pipe parts 41 to 46 as in the embodiment, the space required for placing the heat pipe parts 41 to 46 can be lessened.

Third Embodiment

Next, an electronic apparatus according to a third embodiment of the invention will be discussed with reference to FIG. 5.

In a cooling unit 50 according to the third embodiment, a heat pipe is formed with a first evaporation part 51A that serves as a first heat reception part, a first steam pipe 52A, a first condensation part 53A, a first liquid pipe 54A, a second evaporation part 51B that serves as a second heat reception part, a second steam pipe 52B, a second condensation part 53B, a second liquid pipe 54B, and a third heat reception part 56. The first evaporation part 51A, the first steam pipe 52A, the first condensation part 53A, the first liquid pipe 54A, and the third heat reception part 56 are formed like the first evaporation part 41A, the first steam pipe 42A, the first condensation part 43A, the first liquid pipe 44A, and the third heat reception part 46 of the second embodiment.

The second evaporation part 51B, the second steam pipe 52B, the second condensation part 53B, and the second liquid pipe 54B are formed like the second evaporation part 41B, the second steam pipe 42B, the second condensation part 43B, and the second liquid pipe 44B of the second embodiment; however, the disposition position of coolant flow paths 59 from the second evaporation part 51B to the third heat reception part 56 differs from that in the second embodiment.

The first condensation part 53A and the second condensation part 53B are disposed side by side inside exhaust ports 19. A single electric fan unit 58 is provided for both of the first condensation part 53A and the second condensation part 53B. Air flow sent from the electric fan unit 58 passes through a fin assembly 57B of the second condensation part 53B and then passes through a fin assembly 57A of the first condensation part 53A and is discharged to the outside of a casing 18 through the exhaust ports 19. The air flow sent from the electric fan unit 58 condenses the coolant steam flowing into the second condensation part 53B from the second steam pipe 52B and also condenses the coolant steam flowing into the first condensation part 53A from the first steam pipe 52A.

According to the cooling unit 50 of the embodiment, one electric fan unit is provided corresponding to the two evaporation parts 51A and 51B and the configuration of the cooling unit 50 is simplified. Thus, the space required for placing the cooling unit 50 can be lessened and the cost of the cooling unit 50 can also be reduced.

Fourth Embodiment

Next, an electronic apparatus according to a fourth embodiment of the present invention will be discussed with reference to FIG. 6.

In a cooling unit 60 according to the fourth embodiment, a heat pipe is formed with an evaporation part 61 of a first heat reception part, a steam pipe 62, a condensation part 63, a liquid pipe 64, a second heat reception part 65, and a third heat reception part 66. The evaporation part 61, the steam pipe 62, the condensation part 63, the liquid pipe 64, the second heat reception part 65, and the third heat reception part 66 are formed like the evaporation part 31, the steam pipe 32, the condensation part 33, the liquid pipe 34, the second heat reception part 35, and the third heat reception part 36 of the first embodiment. However, the condensation part 63 is provided with no fin assembly.

The cooling unit 60 according to the fourth embodiment is not provided with an electric fan unit and is provided with a chiller 70 for chilling the condensation part 63 in place of the electric fan unit. The chiller 70 is a device provided independently of heat pipe parts 61 to 66 for circulating a coolant. The chiller 70 includes a pipe member 71, a pump 72, and a heat exchanger 73. The pipe member 71 is in intimate contact with the condensation part 63 and is thermally connected to the condensation part 63.

A coolant flowing through the pipe member 71 takes heat from the condensation part 63 when it flows through the proximity of the condensation part 63. Then, when the coolant flows through the pipe member 71 and arrives at the heat exchanger 73, the heat of the coolant is transmitted to the heat exchanger 73 and further is transmitted from the heat exchanger 73 to the ambient air. The warmed air is discharged to the outside of a casing 18 through exhaust ports 19. Since the pump 72 delivers the coolant passing through the heat exchanger 73 to the pipe member 71, the condensation part 63 is continuously cooled by the coolant.

In a case where difficult to provide an electric fan unit or in a case where difficult to provide the condensation part 63 in the vicinity of the exhaust ports 19 because of the layout of the inside of the casing 18, the cooling unit 60 is preferred. That is, the cooling unit 60 cools the condensation part 63 using the chiller 70, so that an electric fan unit need not be placed and the condensation part 63 need not be placed in the vicinity of the exhaust ports 19 either.

The cooling unit 60 of the fourth embodiment has a set of the evaporation part 61, the steam pipe 62, the condensation part 63, and the liquid pipe 64 like the cooling unit 30 of the first embodiment, but may have two or more sets of evaporation part, steam pipe, condensation part, and liquid pipe like the cooling unit 40 or 50 of the second or third embodiment.

Fifth Embodiment

Next, an electronic apparatus according to a fifth embodiment of the present invention will be discussed with reference to FIG. 7.

In a cooling unit 80 according to the fifth embodiment, a heat pipe is formed with an evaporation part 81 of a first heat reception part, a steam pipe 82, a condensation part 83, a liquid pipe 84, a second heat reception part 85, and a third heat reception part 86. The evaporation part 81, the steam pipe 82, the condensation part 83, the liquid pipe 84, the second heat reception part 85, and the third heat reception part 86 are formed like the evaporation part 31, the steam pipe 32, the condensation part 33, the liquid pipe 34, the second heat reception part 35, and the third heat reception part 36 of the first embodiment.

The cooling unit 80 according to the fifth embodiment is not provided with an electric fan unit unlike the cooling unit of the first embodiment. However, although the cooling unit 80 is not provided with an electric fan unit, the condensation part 83 is cooled by natural air cooling and thus coolant steam can be condensed in the condensation part 83. That is, the heat of the coolant steam in the condensation part 83 is transmitted from the condensation part 83 to a fin assembly 87 and further is transmitted from the fin assembly 87 to the ambient air. The warmed air is discharged to the outside of a casing 18 through exhaust ports 19. Since the cooling unit 80 does not require an electric fan unit, the configuration of the cooling unit 80 is simplified. Thus, the space required for placing the cooling unit 80 can be lessened and the cost of the cooling unit 80 can also be reduced.

The cooling unit 80 of the fifth embodiment has a set of the evaporation part 81, the steam pipe 82, the condensation part 83, and the liquid pipe 84 like the cooling unit 30 of the first embodiment, but may have two or more sets of evaporation part, steam pipe, condensation part, and liquid pipe like the cooling unit 40 or 50 of the second or third embodiment.

In the embodiments described above, the notebook personal computer 10 is described as an example of an electronic apparatus according to the present invention. However, the present invention may be applied to any other type of electronic apparatuses. 

1. An electronic apparatus comprising: a circuit board that is mounted with a first heat generating component and a second heat generating component that generate heat; and a circulation-type heat pipe that circulates a coolants the heat pipe including: a first heat reception part that receives heat from the first heat generating component, the first heat reception part being provided with a wick for evaporating the coolant to serve as an evaporation part; a second heat reception part that receives heat from the second heat generating component and circulates the coolant to the first heat reception part; and a condensation part that condenses the coolant circulated from the first heat reception part, the condensation part being provided between the first heat reception part and the second heat reception part.
 2. The apparatus according to claim 1, wherein the heat pipe further includes a heat sink that is thermally connected to the condensation part.
 3. The apparatus according to claim 2 further comprising a fan that sends air flow to the heat sink.
 4. The apparatus according to claim 3, wherein a flow path of the coolant between the evaporation part and the condensation part is a steam pipe, and wherein a flow path of the coolant between the condensation part and the evaporation part is a liquid pipe.
 5. The apparatus according to claim 4, wherein the circuit board is further mounted with a third heat generating component that generates heat, and wherein the heat pipe further includes a third heat reception part that receives heat from the third heat generating component at a midpoint in the liquid pipe.
 6. The apparatus according to claim 5, wherein the first heat generating component has the largest calorific value with respect to the second heat generating component and the third heat generating component.
 7. The apparatus according to claim 6, wherein the heat pipe is formed by overlapping and joining two thin plate members.
 8. The apparatus according to claim 2 further comprising a chiller that chills the condensation part by circulating a liquid in a pipe member. 